Electronic devices having tapered edge walls

ABSTRACT

An electronic device includes a substrate, a structure over the substrate having an edge wall defining at least a portion of an opening exposing a surface of the substrate, and a dielectric material adjacent and in contact with the edge wall and an adjacent portion of the surface of the substrate. The dielectric material has a profile tapering downward from adjacent the edge wall toward the substrate. Other electronic devices include a substrate and a solder mask over the substrate. The solder mask defines an opening therethrough. A supplemental mask is within the opening of the solder mask, and has a sidewall that slopes away from the solder mask. A conductive structure is adjacent and in contact with at least one of the solder mask or the supplemental mask.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. patent application Ser. No.15/730,272, filed Oct. 11, 2017, the disclosure of which is herebyincorporated herein in its entirety by this reference.

TECHNICAL FIELD

The present disclosure, in various embodiments, relates generally tomethods of processing semiconductor devices and related structures. Moreparticularly, the present disclosure relates to method of alteringtopographies of materials employed in semiconductor device fabrication.

BACKGROUND

Large-scale production of particular types of semiconductor devicesposes problems peculiar to the type of die, electronic circuits,external connectors, and packaging. For example, so-called “flip-chip”dice comprise electronic devices formed on a semiconductor substratewhose integrated circuitry terminates in an array of conductive sites ona die's active surface, which conductive sites are typically referred toas “bond pads.” External conductive structures exemplified by solder“bumps” or “balls” are attached to the bond pads. In use, the flip-chipdie is inverted, positioned atop a substrate with contact pads matchingthe locations of the conductive structures of the die, and theconductive structures bonded to the contact pads of the substrate. Chipscale, flip-chip configured packages are also typically disposed facedown over a higher-level substrate with which the chip scale packagesare to be connected.

In order to fabricate flip-chip dice in large quantities, severalsemiconductor dice are simultaneously fabricated on a wafer. The waferis then scribed or sawn into individual dice, and finishing operationsincluding packaging are conducted on the singulated dice.

It is typically desirable to apply a supportive or protective dielectricmaterial, such as a solder mask, on at least the active surfaces ofsemiconductor devices or substrates, such as organic packagingsubstrates, flip-chip type dice, and chip-scale packages, that will beconnected to another semiconductor device or to higher-level packaging.Polymers, glass, and other electrically nonconductive materials may beapplied to one or both major surfaces of such semiconductor devices.Conventionally, such dielectric materials are applied to a surface of asemiconductor device prior to forming or attaching conductive structuresto bond pads or conductive traces exposed through openings in thematerial. Openings are formed, for example, by etching, in the materialto accommodate the subsequent formation or attachment of conductivestructures in the openings.

When conventional techniques are employed to form such a protectivedielectric material on a surface of a semiconductor device, it isdifficult to form openings in the protective dielectric material andform or attach conductive structures, such as solder bumps or balls, incontact with one another within the openings. Thus, during a TCB(thermo-compression bonding) process, voids may occur in the NCF(nonconductive film, which may also be referred to herein and in the artas a wafer level underfill (WLUF)) between an edge of the protectivedielectric material defining at least part of an opening and a surfaceof a conductive structure therein.

The problem arises due to the abrupt edge of openings resulting fromconventional techniques used to form openings in solder masks, whichresult in abrupt, vertical edge walls of the openings, or even a slightundercut of the edge walls. As a result, a void trapping air between asolder bump and the edge wall of the associated opening may be formed.Voids may occur in various locations, such as along an edge of a soldermask, in between interconnects, or between an interconnect and the sideof the solder mask.

Such voids may present reliability issues, particularly when a flowableNCF is employed between stacked semiconductor devices, and specificallyshorting between adjacent conductive structures. Typically, NCF islaminated onto the wafer prior to dicing the wafer. Therefore the NCF ison the die already during the stacking process. The voids may compromisethe ability of the NCF to provide dielectric isolation between laterallyadjacent conductive structures. The NCF keeps solder from moving acrossmultiple interconnects. If a void bridges multiple interconnects, soldercan fill the void and cause a short. Also, if there is a void next to aninterconnect, the solder can move into the void and cause an openinterconnect. Thus, underfill layers with air pockets or voids may notcompletely support or protect the die or the conductive structuressecured to the bond pads thereof. The increased use of NCF materialsdoes not cure the voiding problem. Voids may cause shorting betweenadjacent traces, semiconductor device delamination from the substrate,and solder flowing into the voids, starving solder joint locations ofsufficient solder to effect a robust interconnection.

FIG. 13 is a photograph showing a y-axis cross-section of interconnects10 and NCF material 12. The interconnects (which may be, for example,Cu, Ni, Sn, or Ag) are electroplated to a semiconductor substrate priorto laminating the NCF material 12 onto the wafer. The structure is thensubjected to TCB, at which point the voids 14, appearing in the lowerright corner of FIG. 13, are formed.

Attempts have been made to eliminate such voids through the use ofmultiple overlapping solder masks, each mask having a slightly largeropening than the mask below, resulting in a stair-step edge wall aroundeach opening. Such attempts are not entirely successful, and add time,cost, and complexity to the fabrication process.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified cross-section of a substrate over which aconductive structure and a solder mask are secured.

FIG. 2 is a simplified cross-section of the substrate shown in FIG. 1after a supplemental mask has been applied.

FIG. 3 is a simplified cross-section illustrating how the supplementalmask shown in FIG. 2 may be applied.

FIG. 4 is a simplified cross-section illustrating different shapes ofthe supplemental mask.

FIG. 5 is a simplified cross-section illustrating another conductivematerial formed adjacent the supplemental mask.

FIG. 6 is a simplified cross-section illustrating another substratehaving a conductive material thereon.

FIG. 7 is a simplified cross-section of the substrate shown in FIG. 6after a mask has been applied.

FIG. 8 is a plan view showing the structure of FIG. 7.

FIG. 9 is a simplified cross-section of the substrate shown in FIG. 7after an underfill material has been applied.

FIG. 10 is a simplified cross-section illustrating a substrate having amaterial thereon, and upon which another material is added by directmaterial deposition to change a topography of the surface.

FIG. 11 is a simplified cross-section illustrating a substrate having amaterial thereon, and upon which another material is added by directmaterial deposition to fill a void.

FIG. 12 is a simplified cross-section illustrating a substrate having amaterial added by direct material deposition to form or alter a flowpath.

FIG. 13 is a photograph showing a y-axis cross-section of interconnectsformed by conventional processes.

DETAILED DESCRIPTION

In some embodiments disclosed herein, methods of processing asemiconductor device are described, as are semiconductor structures.Some methods include providing a material, for example a solder mask,over a major surface of a substrate, depositing particles of anothermaterial by direct material deposition adjacent and in contact with anedge wall of the solder mask to form a supplemental mask over the majorsurface of the substrate. Optionally, a metal material may be depositedover the major surface of the substrate adjacent and in contact with thesupplemental mask.

As used herein, the term “semiconductor substrate” means and includes abase material or construction upon which components, such as those ofmemory cells and peripheral circuitry, as well as logic, may be formed.Semiconductor substrates may include a semiconductor package substrate,a ceramic package substrate, an organic package substrate, or otherpackage substrate. The semiconductor substrate may be a substrate whollyof a semiconductor material, a base semiconductor material on asupporting structure, or a semiconductor substrate having one or morematerials, structures, or regions formed thereon. The semiconductorsubstrate may be a conventional silicon substrate or other bulksubstrate including a semiconductor material. As used herein, the term“bulk substrate” means and includes not only silicon wafers, but alsosilicon-on-insulator (“SOP”) substrates, such as silicon-on-sapphire(“SOS”) substrates or silicon-on-glass (“SOG”) substrates, epitaxiallayers of silicon on a base semiconductor foundation, or othersemiconductor or optoelectronic materials, such as silicon-germanium(Si_(1-x)Ge_(x), wherein x is, for example, a mole fraction between 0.2and 0.8), germanium (Ge), gallium arsenide (GaAs), gallium nitride(GaN), or indium phosphide (InP), among others. Furthermore, whenreference is made to a “semiconductor substrate” in the followingdescription, previous process stages may have been utilized to formmaterials, regions, or junctions, as well as connective elements such aslines, plugs, and contacts, in the base semiconductor structure orfoundation, such components comprising, in combination, integratedcircuitry. Semiconductor substrates may also be, for example, a carrierwafer that does not have components formed therein.

As used herein, spatially relative terms, such as “beneath,” “below,”“lower,” “bottom,” “above,” “upper,” “top,” “front,” “rear,” “left,”“right,” and the like, may be used for ease of description to describeone element's or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. Unless otherwise specified,the spatially relative terms are intended to encompass differentorientations of the materials in addition to the orientation depicted inthe figures. For example, if materials in the figures are inverted,elements described as “below” or “beneath” or “under” or “on bottom of”other elements or features would then be oriented “above” or “on top of”the other elements or features. Thus, the term “below” can encompassboth an orientation of above and below, depending on the context inwhich the term is used, which will be evident to one of ordinary skillin the art. The materials may be otherwise oriented (rotated 90°,inverted, flipped, etc.) and the spatially relative descriptors usedherein interpreted accordingly.

As used herein, reference to an element as being “on” or “over” anotherelement means and includes the element being directly on top of,adjacent to, underneath, or in direct contact with the other element. Italso includes the element being indirectly on top of, adjacent to,underneath, or near the other element, with other elements presenttherebetween. In contrast, when an element is referred to as being“directly on” another element, there are no intervening elementspresent.

As used herein, the terms “comprises,” “comprising,” “includes,” and/or“including” specify the presence of stated features, regions, integers,stages, operations, elements, materials, components, and/or groups, butdo not preclude the presence or addition of one or more other features,regions, integers, stages, operations, elements, materials, components,and/or groups thereof.

As used herein, “and/or” includes any and all combinations of one ormore of the associated listed items.

As used herein, the singular forms “a,” “an,” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

Embodiments are described herein with reference to the illustrations.The illustrations presented herein are not meant to be actual views ofany particular material, component, structure, device, or system, butare merely idealized representations that are employed to describeembodiments of the present disclosure. Variations from the shapes of theillustrations as a result, for example, of manufacturing techniquesand/or tolerances, are to be expected. Thus, embodiments describedherein are not to be construed as being limited to the particular shapesor regions as illustrated, but include deviations in shapes that result,for example, from manufacturing. For example, a region illustrated ordescribed as round may include some rough and/or linear features.Moreover, sharp angles that are illustrated may be rounded, and viceversa. Thus, the regions illustrated in the figures are schematic innature, and their shapes are not intended to illustrate the preciseshape of a region and do not limit the scope of the present claims.

The following description provides specific details, such as materialtypes and processing conditions, in order to provide a thoroughdescription of embodiments of the disclosed compositions and methods.However, a person of ordinary skill in the art will understand that theembodiments of the present disclosure may be practiced without employingall these specific details.

Any fabrication processes described herein do not form a completeprocess flow for processing semiconductor devices. Preceding,intermediary, and final process stages are known to those of ordinaryskill in the art. Accordingly, only the methods and semiconductorstructures necessary to understand embodiments of the present devicesand methods are described herein.

Reference will be made to the drawings, where like numerals refer tolike components throughout. The drawings are not necessarily to scale.

Disclosed are methods of processing semiconductor devices. Some methodsinclude providing a patterned mask over a major surface of a substrate,the mask defining at least one opening therein, and depositing particlesof material by direct material deposition adjacent and in contact withthe mask to form a supplemental mask over the major surface of thesubstrate.

In some embodiments, methods include forming a dielectric material overand in contact with a surface of a substrate adjacent and in contactwith a side wall of a structure on the substrate by direct materialdeposition. The dielectric material may have a surface profile tapereddownwardly from the side wall toward the substrate.

FIG. 1 illustrates a simplified cross-section of a substrate 102 bearinga conductive structure 110, for example a bond pad or a conductivetrace, and over which a solder mask 104 is located. The substrate 102may be any semiconductor substrate, such as an SOI substrate, an SOSsubstrate, an SOG substrate, etc., having integrated circuitry thereon.The substrate 102 may be a printed circuit board or a component thereof.The solder mask 104 may be a dielectric material configured to inhibitsolder material from flowing away from the conductive structure 110 onthe substrate 102. The solder mask 104 may comprise a polymer, such asan epoxy. The solder mask 104 may be provided over a major surface 103of the substrate 102 by techniques known in the art, and may, forexample, be patterned after application thereof by photolithography.

The solder mask 104 may define an opening 106 therein, through which themajor surface 103 and/or the conductive structure 110 or a portionthereof is exposed. As shown in FIG. 2, a supplemental mask 108 may beformed over the major surface 103 of the substrate 102 and adjacent andin contact with an edge wall 105 of the solder mask 104, which definesat least a portion of a boundary of opening 106. The supplemental mask108 may be applied by depositing droplets or other particles of materialin an additive manufacturing process, which may also be characterized asa direct material deposition process. Such processes include, withoutlimitation, material jetting (i.e., ink-jet printing, such as isemployed in 3-D printing) and aerosol jet printing, also known asMaskless Mesoscale Materials Deposition (M3D). The supplemental mask 108may be formed to cover an interface between the edge wall 105 of thesolder mask 104 and the major surface 103 of the substrate 102. Thesupplemental mask 108 may include, for example, a polyimide, apolyimide-like material, an epoxy, an epoxy-acrylate, a wax-basedmaterial, etc. The supplemental mask 108 may comprise the same materialas the solder mask 104 or a different material than the solder mask 104.The material of the supplemental mask 108 may be formulated, forexample, to cure under application of ultraviolet (UV) radiation, or toheat-cure, or both.

FIG. 3 illustrates how the supplemental mask 108 may be formed. In adirect material deposition process, small droplets of a liquid materialmay be expelled from one or more nozzles 156, 158 (which may comprisehundreds or even thousands of nozzles) over the substrate 102.

At the time of the deposition of the particles to form the supplementalmask 108, a distance x between the nozzles 156, 158 and the majorsurface 103 of the substrate 102 or the surface of the conductivestructure 110 may be from about 0.05 mm to about 5 mm, such as fromabout 0.1 mm to about 2 mm, or even from about 0.5 mm to about 1 mm.Thus, the deposition of the supplemental mask 108 may be performed withthe nozzles 156, 158 contacting neither the substrate 102, nor theconductive structure 110, nor the solder mask 104.

The droplets of the liquid material may have volumes in a range from,for example, about 0.5 picoliter to about 1 nanoliter. For example, insome embodiments, the droplets may have a volume of about 30 picoliter.In some embodiments, the droplets may have mean diameters in a rangefrom, for example, about 100 nm to 50 μm, such as from about 500 nm toabout 20 μm, or from about 700 nm to about 5 μm. The mean diameter ofthe droplets may be approximately equal to the diameter of the nozzle156, 158 from which the droplets exit. Thus, the nozzles 156, 158 mayalso have diameters in a range from, for example, about 100 nm to 50 μm,such as from about 500 nm to about 20 μm, or from about 700 nm to about5 μm.

The liquid material may have a viscosity in a range from, for example,about 0.1 centiPoise (cP) to about 1000 cP, such as from about 1 cP toabout 100 cP, or from about 2 cP to about 20 cP. Suitable materials areoffered, for example, by Dow Chemical Company, of Midland, Mich.; E.I.du Pont de Nemours and Company, of Wilmington, Del.; Taiyo America,Inc., of Carson City, Nev.; and JNC Corporation, of Tokyo, Japan. Asuitable inkjet printer for implementation of embodiments of thedisclosure is offered commercially by Meyer Burger (Netherlands) B.V.

The supplemental mask 108 may be formed to have a maximum thickness, asmeasured from the major surface 103 of the substrate 102 or from anexposed surface of the conductive structure 110 to an upper extent ofthe supplemental mask 108, in a range from about 1 μm to about 1000 μm,such as from about 5 μm to about 500 μm, or from about 10 μm to about100 μm. The maximum thickness of the supplemental mask 108 may beselected to be approximately the same as the thickness of the soldermask 104, or approximately the same as the difference in thicknessbetween the solder mask 104 and the conductive structure 110.

The nozzles 156, 158 may be arranged to have any selected orientationwith respect to the substrate 102. For example, the nozzle 156 is shownas expelling particles at an oblique angle to the major surface 103 ofthe substrate 102. The nozzle 158 is shown as expelling particles normal(i.e., perpendicular) to the major surface 103 of the substrate 102. Theorientation and placement of the nozzles 156, 158 may be used toinfluence the shape of the supplemental mask 108 formed on the substrate102 and to ensure that the material of supplemental mask 108 adheres tothe edge wall 105 of the solder mask 104, to the substrate 102, orconductive structure 110. Furthermore, though only two nozzles 156, 158are shown in FIG. 3 for simplicity of illustration, any suitable numberof nozzles may be used to deposit the particles that form thesupplemental mask 108. The nozzles 156, 158 (including any other nozzlesnot shown in FIG. 3) may be used to simultaneously expel particles ontothe substrate 102. In some embodiments, some of the nozzles 156, 158 mayexpel particles onto the substrate 102 at the same time that othernozzles 156, 158 are inactive. The nozzles 156, 158 to be used at anygiven time may be selected based on the cross-sectional shape (e.g.,profile) of the supplemental mask 108 to be formed. That is, particlesmay be selectively expelled from a subset of the nozzles 156, 158 at onetime, and from a different subset of the nozzles 156, 158 at a differenttime. The nozzles 156, 158 may be configured to deliver particles withinabout + or −10 μm, within about + or −5 μm, or even within about + or −1μm of a selected location. That is, the nozzles 156, 158 may have aprecision within about 10 μm, within about 5 μm, or even within about 1μm. The nozzles 156, 158 may deliver particles over the same portion ofthe substrate 102 in a single pass or in multiple passes to produce thesupplemental mask 108 having a selected cross-sectional shape. Forexample, the nozzles 156, 158 may be used to “build up” the supplementalmask 108 by applying particles over the same position on the substrate102 multiple times.

FIG. 4 illustrates some different cross-sectional shapes in which thesupplemental mask 108 may be formed, which may be arcuate. For example,the portion of the supplemental mask 108 on the left of the opening 106has a surface curved inward (i.e., concave) toward the interface betweenthe solder mask 104 and the substrate 102. The portion of thesupplemental mask 108 on the right of opening 106 has a surface curvedoutward (i.e., convex) away from the interface between the solder mask104 and the substrate 102. Furthermore, and as shown in FIG. 2, thesurface of the supplemental mask 108 may have a linear profile in theplane of view shown in FIG. 2.

The supplemental mask 108 may be formed such that the surface of thesupplemental mask 108 intersects the major surface 103 of the substrate102 at an angle between about 10° and about 80°, such as between about30° and about 60°, or even about 45°. In other words, the supplementalmask 108 may form a solder mask opening having an inwardly tapered sidewall (i.e., sloping away from the solder mask 104).

As shown in FIG. 5, another conductive material 112 may optionally bedeposited over the conductive structure 110 adjacent the supplementalmask 108. For example, a solder bump may be deposited or formed withinthe opening 106 defined by the supplemental mask 108 and the conductivestructure 110. In some embodiments, the conductive material 112 may beor may connect to a pillar or other structure. The conductive material112 may include, for example, solder, gold, copper, a conductive resin,or a conductor-filled resin.

FIG. 6 illustrates a simplified cross-section of a substrate 202. One ormore conductive structures 204, for example conductive traces, may beformed over a major surface 203 of the substrate 202 within an openingin a mask 205. The conductive structures 204 may be formed by any methodknown in the art, such as screen printing, blanket metal filmapplication, electrolytic deposition and photolithographic patterning,patterning a seed material and electroless deposition, laser resistablation and etching of an underlying metal material, etc.

As shown in FIG. 7, mask elements 206 may be applied over the majorsurface 203 of the substrate 202 adjacent the conductive structures 204and the mask 205. The mask elements 206 may be applied by directmaterial deposition or additive manufacturing as described above, andall the material properties, conditions, and permutations discussedabove may be used to form the mask elements 206. The mask elements 206may entirely surround the interface between the mask elements 206 andthe substrate 202 within the opening in the mask 205.

FIG. 8 is a plan view showing the mask 205, conductive structures 204,and mask elements 206 depicted in FIG. 7. As shown in FIG. 8, the maskelements 206 may be sloped to surround edges of the conductivestructures 204, and may overlap one another. The structure substrate202, conductive structures 204, and mask elements 206 shown in FIGS. 7and 8 may form an electronic device. The conductive structures 204 mayhave an edge wall defining at least a portion of an opening exposing asurface of the substrate 202. The mask elements 206 may be a dielectricmaterial adjacent and in contact with the edge wall and an adjacentportion of the surface of the substrate 202. The mask elements 206 mayhave a profile tapering downward from adjacent the edge wall toward thesubstrate 202 (FIG. 7) below the mask 205.

The mask elements 206 may limit or prevent separation of the conductivematerial 204 from the substrate 202 at the bondline during subsequentprocessing. In some embodiments, and as shown in FIG. 9, the substrate202 may be subjected to a WLUF process, yet mask elements 206 mayprevent void formation adjacent areas of contact between the conductivestructures 204 and the substrate 202. An underfill material 208 may beapplied over the mask elements 206. The underfill material 208 may be anonconductive epoxy-based material, and may be applied at a thicknessfrom about 10 μm to about 50 μm.

The supplemental mask 108 (FIGS. 2-5) and the mask 206 (FIGS. 7-9)disclosed herein may have various other benefits. For example, masks asdescribed may provide lateral support for other features on asemiconductor substrate, such that the semiconductor structure is moremechanically robust.

As another example, masks may be formed to have a shape that alters apath through which another material may flow, such that areas ofpotential voids are eliminated and air is pushed out of areas betweenthe mask and another material flowing over the mask. This benefit maylimit the occurrence of problems common in conventional methods, such asthe creation of a conductive path between adjacent solder bumps ortraces, semiconductor device delamination from a substrate, voids whichundesirably fill with solder, starving an interconnect so that solderflows out and creates an open, and problems with device reliability.Such benefits may be particularly valuable in helping to eliminate voidsfrom forming at an interface between a die and a substrate. Otherbenefits may include, for example, formation of ball grid array (BGA)packaging, in which solder balls are arranged in a compact grid on asubstrate.

Masks and methods of forming masks as disclosed herein may be beneficialfor filling any open area on a semiconductor or other substrate. Forexample, direct material deposition or additive manufacturing may beused to fill in an opening over a conductive plug formed in asemiconductor structure, or may be used to form a tapered structure orother topography.

In some embodiments, a method comprises applying a material to anexposed surface to alter the topography thereof. For example, FIG. 10illustrates a simplified cross-section of a substrate 302 having amaterial 304 thereon. As shown, a surface 306 of the material 304 may berough or irregular. Using direct material deposition, another material308 may applied over the material 304. The resulting surface 310 of thematerial 308 may have a lower roughness or irregularity than the surface306 of the material 304. In some embodiments, the material 308 may bedeposited directly on the substrate 302. In certain embodiments, thesurface 310 may have a higher roughness or irregularity in topographythan the surface 306.

In certain embodiments, and as shown in FIG. 11, the material 304 maydefine an opening 312 therein, and the material 308 may be applied tosubstantially fill the opening 312. The surface 310 of the material 308may be coplanar with the surface 306. In other embodiments, additionalmaterial 308 may be added to cover the surface 306 of the material 304.

In some embodiments, and as shown in FIG. 12, the material 308 may beused to form or alter a flow path 314 through which a flowable material,for example an encapsulant material, may be directed across thesubstrate 302.

Another advantage of processes as disclosed is that supplierspecifications may be relaxed as compared to conventional processes.That is, direct material deposition or additive manufacturing may beused to form masks that can cover imperfections in substrate surfacesand bondlines that would cause failure in conventional processes. If thesupplier specifications are more relaxed, the cost of parts (e.g.,substrates, with or without conductive materials thereon) may be lower,and it may be easier to manage the supply chain (e.g., because defectsor deviations in workpieces are less likely to cause a stoppage inmanufacturing, because multiple suppliers may be able to meetspecifications, etc.).

Direct material deposition or additive manufacturing may also be used tosmooth out abrupt topography changes on substrates, which abrupttopography changes can cause voids and other imperfections. This may beparticularly valuable in the formation of DRAM (dynamic random-accessmemory), 3DI (three-dimensional integration) packages, which have higherbandwidth and operate at higher speeds than memory meeting earlierstandards.

While the disclosed device structures and methods are susceptible tovarious modifications and alternative forms in implementation thereof,specific embodiments have been shown by way of example in the drawingsand have been described in detail herein. However, it should beunderstood that the present disclosure is not intended to be limited tothe particular forms disclosed. Rather, the present inventionencompasses all modifications, combinations, equivalents, variations,and alternatives falling within the scope of the appended claims andtheir legal equivalents.

1. An electronic device, comprising: a substrate; a structure over thesubstrate having an edge wall defining at least a portion of an openingexposing a surface of the substrate; and a dielectric material adjacentand in contact with the edge wall and an adjacent portion of the surfaceof the substrate, the dielectric material having a profile taperingdownward from adjacent the edge wall toward the substrate.
 2. Theelectronic device of claim 1, wherein the profile comprises a profileselected from the group consisting of a linear profile, a concaveprofile, and a convex profile.
 3. The electronic device of claim 1,wherein the structure comprises a mask structure.
 4. The electronicdevice of claim 1, wherein the structure comprises a conductivestructure.
 5. The electronic device of claim 4, wherein the conductivestructure comprises a trace or a bond pad.
 6. The electronic device ofclaim 1, wherein the dielectric material entirely surrounds an interfacebetween the structure and the substrate.
 7. The electronic device ofclaim 1, further comprising an underfill material over the dielectricmaterial.
 8. The electronic device of claim 7, wherein the underfillmaterial comprises a nonconductive epoxy-based material.
 9. Theelectronic device of claim 7, wherein the underfill material has athickness from about 10 μm to about 50 μm.
 10. An electronic device,comprising: a substrate; a solder mask over the substrate, the soldermask defining an opening therethrough; a supplemental mask within theopening of the solder mask, the supplemental mask having a sidewall thatslopes away from the solder mask; a conductive structure adjacent and incontact with at least one of the solder mask or the supplemental mask.11. The electronic device of claim 10, further comprising anotherconductive material over and in contact with the conductive structure.12. The electronic device of claim 11, wherein the another conductivematerial comprises a pillar.
 13. The electronic device of claim 11,wherein the another conductive material comprises a material selectedfrom the group consisting of solder, gold, copper, a conductive resin,and a conductor-filled resin.
 14. The electronic device of claim 10,wherein the supplemental mask intersects a major surface of thesubstrate at an angle between about 10° and about 80°.
 15. Theelectronic device of claim 10, wherein the supplemental mask exhibits aconcave surface.
 16. The electronic device of claim 10, wherein thesupplemental mask exhibits a convex surface.
 17. The electronic deviceof claim 10, wherein the supplemental mask has a maximum thickness in adirection normal to a major surface of the substrate, in a range fromabout 1 μm to about 1000 μm.
 18. The electronic device of claim 10,wherein the solder mask comprises a polymer.
 19. The electronic deviceof claim 18, wherein the solder mask comprises an epoxy.
 20. Theelectronic device of claim 10, wherein the substrate comprises a printedcircuit board.